The city Economic Development Corp. released a feasibility study Wednesday that examined how extending the subway to Secaucus would stimulate ridership and “leverage existing investments” — like the city-financed extension of the 7 line west to 11th Avenue, a key legacy project of the mayor’s three terms in office.

The city hired consultants Parsons Brinckerhoff in early 2011 to study the merits of extending the subway, shortly after New Jersey Gov. Chris Christie canceled the planned “Access to the Region’s Core” cross river tunnel project, a blow to those who believe the region is hampered by the limited capacity for trains crossing the Hudson between Manhattan and the suburbs.

“It’s been a century since there was a new rail tunnel under the Hudson, and demand for travel between New Jersey and Manhattan is growing rapidly and quickly exceeding the capacity of existing transit infrastructure,” Bloomberg said Wednesday morning, through a spokeswoman. “The lack of new transit investment is creating a serious and urgent threat to New York City’s economic competitiveness.

“Extending the 7 train to Secaucus is a promising potential solution – it would leverage existing investments and be compatible with other proposed projects – and is deserving of serious consideration. We look forward to continuing to discuss this option, as well as other feasible proposals, with the numerous stakeholders involved.”

Under the proposal examined by Parsons Brinckerhoff, the No. 7 train would cross the river through a tunnel and connect with the existing Frank R. Lautenberg Station in Secaucus. The extension would improve access from the suburbs through Midtown, the yet-to-be-built Hudson Yards development on the West Side, and through the existing 7 train corridor into Queens.

The project would “require” that one part of the current westward extension of the 7 be revived: the MTA and the city dropped a planned station at 10th Avenue from the extension because of its projected cost. The move would also require improvements at busy stations already served by the 7, including Grand Central, Times Square, and 5th Avenue/Bryant Park.

A 7 train extension could support 128,000 riders per day, with up to 30 trains per hour during the morning and evening rush, the study says. It would take about 16 minutes for trains to run from the Secaucus station to Grand Central.

The extension would not interfere with the other major river crossing project that has been championed since the demise of the ARC project: Amtrak’s Gateway project, which would add new tunnels to connect the northeast corridor lines in New Jersey to Penn Station in Manhattan.

The MTA’s press office did not immediately offer a response. But in the past, the MTA, a New York state authority that is busy trying to manage sizable debt, infrastructure and labor management challenges of its own, has been dismissive of the 7 plan.